A skateboard is comprised of an elongated board with a pair of trucks attached underneath. Each truck is comprised of a base plate that is attached to the board with mounting bolts, and a hanger that is attached to the base plate with a king pin bolt. The hanger has two lateral arms through which an axle is embedded. The hanger has an upwardly projecting pivot pin which is positioned inside a pivot pin receiving hole in the base plate. The king pin bolt is positioned through an oversized hole in a main body portion of the hanger. The bolt is centered within the hole by two flat bottomed, elastomeric bushings each seated in a shallow, cylindrical shaped bushing seat on either side of the hanger. The king pin bolt and the pivot pin form a divergent angle in the direction towards the board. When the board is rolled about a longitudinal axis to either side by foot pressure, the hanger is pivoted about the pivot pin to steer the wheels in a corresponding direction. The trucks are mounted as mirror images of each other, so that they simultaneously steer in opposite directions in response to board roll.
The elastomeric bushings provide compliance to enable the bolt to move laterally within the oversized hole in the bushing seats, and to provide increasing roll resistance with increasing roll angle of the board. Roll resistance is determined by the size, shape, hardness and positioning of the elastomeric bushings, and also by the clamping force applied on the bushings by the bolt, which is adjustable for tuning bushing compression and board roll resistance. The bushings must provide enough resistance to prevent the wheels from steering too easily, that is, to provide suitable directional stability. Higher resistance provides good directional stability but limits turning radius, whereas lower resistance enables a tight turning radius but sacrifices some directional stability.
Currently, prior art skate technology does not provide a quick or efficient method of making bushing tension or bushing position adjustments on a skateboard truck. For bushing tensioning purposes, current adjustment procedures demand that a rider dismount and turn over the skateboard, and then use tools such as a wrench, allen key or skate tool to effect such tensioning adjustments. As for bushing position adjustments, prior art currently provides only for the replacement of one bushing with another, and doesn't address the many benefits to be found by controllably rotating the position of the bushings, within their respective bushing seats, on the truck itself. This limitation is largely due to the fact that current skate technology predominantly uses flat bottomed, cylindrical shaped skateboard bushings wherein the act of rotating such bushings within their corresponding bushing seats provides little or no functional benefit to the operation of a skateboard.
Other bushing shapes, uncommon as they are, utilize bushings in a fixed position, presumably to gain the most rebound or ‘return to center’ from the bushings, or else, to obviate the need for the use of a pivot pin in the truck mechanism for the controlled turning of the skateboard. For example, U.S. Pat. No. 6,523,837 to Kirkland (and related U.S. Pat. No. 6,315,304 to Kirkland et al.) discloses a skateboard truck having an adjustment ring which is used to manually rotate a cam surface adjacent one end of a bushing. Mating cam surfaces in the hanger act to compress/decompress the bushing when the adjustment ring is rotated.
It would thus be desirable to provide a truck bushing and a method of easily controlling the rotation of the truck bushing so as to quickly and without the use of tools facilitate a change in the desired roll resistance of the truck relative to the board and thus provide increased control over the steering and handling characteristics of the skateboard.